The need for low power circuits has increased significantly due to the tremendous growth in small, portable battery-powered devices and IC (Integrated Circuit) chips that support such devices. Oscillators are important to the efficient operation of such IC chips and associated electronic components and devices due to their ability to provide oscillating output signals for timing and other operations.
One example of an oscillator is a low power oscillator, which can be designed to function with low power applications that, for example, rectify a digital signal to supply an IC chip. In such cases, the power supply for the IC chip has limited loading capability. This means that the oscillator is expected to consume low power during operations. A current controlled ring oscillator is typically used in such situations because it may consume an order less power compared to other types of oscillators such as, for example, a relaxation oscillator.
A low power ring oscillator may output a middle rail signal before it oscillates during the startup phase, which can result in an excessive short-through current from, for example, one or more logic gates that load the oscillator. Such a power consumption peak during the startup phase can collapse the system or cause malfunctions. Thus, an important goal involves minimizing the startup current associated with an oscillator as much as possible.